Tahoe City Water Runoff Treatment Facility to Receive Needed Maintenance

June 03, 2015

The filter was clogged and needed replacing.

In 1997, as part of the Tahoe City Urban Improvement Project, the county’s Department of Public Works constructed the Tahoe City Storm Water Treatment Facility. The treatment system uses an upper detention pond that connects to a lower pond that holds manmade wetlands. These wetlands are planted with vegetation designed to capture sediment-filled stormwater runoff. The vegetation filters out the sediment, preventing nutrients from reaching the lake.

Over time, the wetlands has collected thick layers of organic material that have reduced the storage capacity, blocked the channel between the two ponds, reduced treatment efficiency, and increased the risk of flooding. Because of the blockage, downtown Tahoe City experiences flooding during large storms.

“This 18-year-old project has done exactly what it was designed to do: prevent sediment from reaching Lake Tahoe,” said Supervisor Jennifer Montgomery, whose 5th District includes about 40 percent of Lake Tahoe. “It’s time for some maintenance to allow this facility to continue its role in protecting the basin’s environment.”

On Tuesday, the Board of Supervisor authorized Public Works to solicit bids for a project to restore the wetlands area to its 1997 state. The first phase of the project consists of hauling off the organic matter, grading the wetland area to the original conditions, and seeding and planting the disturbed area with appropriate wetlands vegetation. The second phase will be restoration of the detention pond. The project is located on about two acres located between State Route 89 and Fairway Drive in Tahoe City.

This treatment facility is one of several built by Placer County to reduce the amount of runoff entering Lake Tahoe. As runoff from storms and snowmelt crosses impermeable surfaces in the Tahoe Basin, it collects nutrient-laden sediment, which is then deposited into the lake. Nutrients spur the growth of algae that decreases the lake’s clarity. This is one of many Placer County projects designed to prevent that.